Cryptosporidium parvum is an important causative agent of diarrhea in humans and animals worldwide. It is particularly associated with morbidity an mortality in immunocompromised individuals including AIDS patients. There is currently no effective therapy for cryptosporidiosis in large part due to a poor understanding of its basic biology and pathogenicity. Results of recent microbial genome sequencing projects have validated this strategy as a cost-effective and time-efficient approach to study the biology of microbial pathogens. The goal of this project is the complete nucleotide sequence analysis of the 10.4 mbp C. parvum NEMC1 genotype 1isolate genome. A total genome shotgun approach will provide > 99 percent of the NEMC1isolate genome. In parallel, Project 2 of the IRPG will sequence the IOWA genotype will be sequenced to >99 percent coverage to provide an extensive overview of the similarities and differences between genotype 1 and genotype 2 isolates. BAC clones will also be generated and will be used to generate minimum tiling path contigs, and provide a basis for finish sequencing in. The final sequence will provide a powerful tool to enhance the basic understanding of the biology and pathogenesis of C.parvum with the ultimate long-term goal of development of new safe and effective strategies for interventions in cryptosporidiosis.